I have always faced challenges understanding Performance related terminologies. Underlying concepts within performance of a system seems convoluted. The very basic performance measure is the time between a request and a response. For diagnostic purpose, it necessitates the need of understanding the underlying concepts of performance. The ideas is that if we are able to understand internal nitty gritty of performance of a system, we will be able to make better design decision. Also, this will help Quality Assurance team create a performance test strategy. Above diagram tries to explain the internal nitty-gritty of performance component of a system. QA would generally ask, what kind of testing needs to be performed on a web application. The answer is definitely not straight forward, but dependent on following, but not limited to, criteria: Is this Web Application built from scratch based on some open platform? Is this a SaaS Application? How much control